A “ front row seat ” at the birth of a comet



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As Douglas Adams said: Space is big. Really big. Therefore, scientists only see tiny shards of space at any given time, so on the rare occasion that something new is observed, it’s an eye-opening delight.

Astronomers recently saw an enigmatic icy object in Jupiter’s shadow begin to transform into a type of comet, which sticks close to the sun. This is the first time they have watched this happen.

The object, named LD2, is called a Centaur, a frozen proto-world named after half-person, half-horse mythological creatures because these orbs can behave like an asteroid and a comet. The centaurs hang out between Jupiter and Neptune. Constantly attracted by the gravity of gas and ice giants, they are usually either thrown out of the solar system or thrown toward the sun. In this case, they become hyperactive comets, orbiting the sun along a highly elliptical running track that does not extend too far beyond Jupiter.

According to a study published last month in The Astrophysical Journal Letters, the chaos of this gravitational battle royale has determined that LD2 will take hold in the inner solar system. In forty-three years this Centaur’s transition will be complete. It will be bubbly and bubbling as it is braised by the sun, becoming the last member of the so-called Jupiter family of comets.

The migration of soggy comets and asteroids from the fringes of our stellar quarter to the rocky inner worlds was like a water utility in the early days of the solar system, quenching the thirst of planets drying up from the giant impacts and planetary magmatic oceans. The encroachment of LD2 will allow astronomers to see what happens when a pristine icy object makes a daring dive into the sun, providing an illuminating echo of eras past.

Meg Schwamb, an astronomer from Queen’s University Belfast who was not involved in the study, said scientists tended to only get snapshots of space phenomena. This time, we see a whole cosmic process unfolding from start to finish. “We have a front row seat,” she said. “You can get out your popcorn.”

Several million years ago, LD2 was an icy object beyond the orbit of Neptune. The planet’s gravity trapped her and brought her into the space between Jupiter and Neptune.

In 2019, the Asteroid Terrestrial-impact Last Alert System or ATLAS, a pair of NASA-funded telescopes developed by the University of Hawaii that research potential space rocks that are killing the city and crushing the country, spotted a object that seemed to trace Jupiter. orbital trajectory. Astronomers called it P / 2019 LD2, or LD2 for short.

Upon closer inspection, its orbit turned out to be strangely wobbly. Orbital calculations suggest that it got a little too close to Jupiter’s massive gravitational force in 2017. Like a cyclist circling a velodrome encountering a sharp, steep drop, LD2 was knocked off balance, putting it on the line. right way to fall and ultimately stay mostly inside, the inner solar system.

It also turned out to be rather excitable: Astronomers could see icy matter escaping forming a hazy cloud called a coma, and a tail exploding in the ink beyond. But her coma lacks water vapor, said Teddy Kareta, a graduate student in planetary astronomy at the University of Arizona and co-author of the study. Combined with models of its orbital evolution, this suggests that LD2 has not yet visited the inner solar system. Scientists caught it at the start of its first trip to the warmer region around our sun.

By 2063, LD2 will revolve around our local star at breakneck speeds, orbiting roughly every six years. Being close enough to the sun, its water ice will constantly be erased, fueling a water vapor coma. “And the activity driven by water is generally what we think of as a comet,” said Jordan Steckloff, a researcher at the Planetary Science Institute in Tucson, Ariz., And lead author of the study.

Considering the epic length of astronomical timescales, LD2’s fleeting saga is unusual. Its evolutionary journey unfolds at the same pace as our daily existence. A young astronomer can go through their entire transition from youth to cometary adulthood and still be alive at its conclusion.

The ephemeral of LD2 is not lost on scientists. “Seeing something so fleeting, changing – it’s a reminder that the solar system is dynamic,” said Dr Schwamb. “He’s a changeable being, in a sense, just like us.

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